Manhole cover and frame



Feb. 22 1 938. v, ELKINGTQN 2,109,287

MANHOLE COVER AND FRAME Filed Nov. 1, 1935 s Sheets-Sheet 1 v. ELKINGTON 2,109,287

MANHOLE COVER AND FRAME Filed Nov. 1, 1955 3 Sheets-Sheet 2 &

Feb, 22, 193. v. ELKINGTON MANHOLE COVER AND FRAME Filed Nov. 1, 1935 3 Sheets-Sheet 3 Patented Feb. 22, 1938 PATENT OFFICE MANHOLE COVER AND FRAME Vivian Elkington, Dover, England Application November 1, 1935, Serial No. 47,857

In Great Britain November 9, 1934 9 Claims.

'stallations or cable or pipe line trench covers and the like, hereinafter termed manhole covers.

The primary object of the invention is to provide a manhole cover in which the frame is of extremely light construction and yet which will be of adequate strength and rigidity when laid on thesite. A further object is to provide a construction of frame which will cast so as to be initially stressfree and which will be substantially fool-proof in setting without the possibility of deformation 15 or winding" of the frame occurring, thereby allowing of a machine-tool fit between cover and frame to render the manhole construction wateror gas-tight without the use of liquid seals or the like. A still further object is to provide a construction of frame which may be easily lifted and reset if and when the surface level of a road, pavement or yard in which the frame is set has to be altered.

According to the invention the frame of a manhole cover is of channel section open at the bottom, the inner side wall of the channel which constitutes the seating surface for the cover being inclined over at least a partof its depth and the upper part of the frame section being provided with apertures through which concrete can be filled into the space enclosed by the channel section, for instance on the site.

The said seating surface may be curved, a part of the said curved seating surface being capable of producing reaction to a force exerted on the cover and having a large vertical component, the composite curved seating surface operating over the whole area to support the cover.

The aforesaid inner side wall may comprise an inclined part and a substantially horizontal part and preferably consists of two upper andlower inclined parts separated by the substantially horizontal part. The lower inclined part may advantageously be formed as a radiused abutment for the. cover preventing development of any cover movement when traffic is passing over it, whilst permitting free opening and closing of 1 the cover.

Embodiments of the invention will now be more particularly described by way of example with reference to the accompanying drawings, where- Figure l is a plan view of a manhole cover according to the invention with the cover in the closed position,

Figure 2 is a section on the line 2-2 of Figure 1,

Figures 3 and 4 are similar views to Figures 1 and 2 showing details of a fixing screw which may be employed when it is desired to have the cover positively attached to the frame,

Figures 5, 6, and 7 are details drawn to an enlarged scale of three forms of corner joint which may be formed between the frame sections,

Figures 8 is a view of the section face on the line 8-8 of Figure 5 or 6. I

Figure 9 is a perspective view of the section face across the joint in Figure '7,

Figure 10 is a plan view of part of cover and frame,

Figure 11 is a, sectional elevation on the line ll-I| of Figure 10,

Figure 12 is a plan view of one of a series of removable cross bars which may be employed in conjunction with the frame of medium and large span trench covers,

Figure 13 is a cross section substantially on the line l3l3 of Figure 12, and

Figure 14 is a section substantially on the line l4-|4 of Figure 12.

Referring to Figures 1 and 2, the frame is composed of four sections l5 cast separately and bolted or otherwise secured together to form the substantially rectangular frame shown in Figure 1. The frame sections I5 are of channel section open at the bottom as shown in Figure 2 and the inner side wall of the channel constitutes a seating surface for the cover "5 which seating surface is curved, and a part of which is capable of producing reaction to a force exerted on the cover and having a large vertical component, the composite curved seating surface operating over its whole area to support the cover. As shown, the inner side wall is inclined at l1 and IS, the inclined surfaces I1 and 19 being connected by a substantially horizontal intermediate surface Ill. The whole surface comprising the surfaces H,

l8, l9, being in actual metal to metal contact with similarly formed surfaces 28, 29, 30 on the cover referred to hereinafter constitutes therefore a continuous seating surface, the whole of which mutually supports the cover and therefore the loads imposed on its top surface. The horizontal intermediate surface l8 prevents the cover when heavily loaded from acting as a wedge and exerting a bursting force inside the frame. The frame sections are cast with main webs 22 and subsidiary webs 23 (see also Figures 3 and 5 to '7) between the collateral parts of the channel section which impart a more or less box or open a trench grid formation to the frame sections. In like manner the cover I6 has main webs 24 and subsidiary webs 25 running between the main webs. The cover is cast with apertures 26 between the subsidiary webs 25 and the upper part of each frame section I5 is cast with apertures 20 therein.

If the frame is cast in sections l5 as described, the sections maybe secured together on the site and when the complete frame has been set on a cement composition bed as usual, grouting is filled into the apertures 20 and sets in the cavities 2| to provide a solid reinforced construction of great strength. Alternatively the frame can be filled with concrete from the bottom and then set in position. In setting the frame in the cement composition bed, the frame may be pressed down through the composition directly on to packings provided for its reception so that the displaced composition rises internally into- Grouting is then filled by the displaced cement composition. The cover It may be filled with concrete, wood-blocks or the like 52 and if concrete is. employed as the filling, a board is placed beneath the cover to close the apertures 26 during filling. In like manner, if the frame is assembled and filled with concrete at the depot, for example, instead of on,

the site,'it is placed upon a board during filling. Carborundum grains may be incorporated into the top surface of the concrete of the cover and in the apertures 20 of the frame in order to obtain a non-skid surface. I

The cover I6 may be lifted out vertically by inserting lifting keys in the keyholes 21 or is easily slidout in a more or less horizontal direction along the curved surfaces between l8 and IS with each of which curved surfaces it makes a substantially line contact when being slid out. As previously stated the edges of the cover l6 are formed by surfaces 28, 29, 30 which are the exact counter-part of the surfaces l1, I8, IQ

of the frame and the lower inclined surface l9 Y of the frame forms a radiused abutment for the surface part 30 of the cover which is similarly radiused thereby rendering any other form of stop unnecessary. When one end of the cover is lifted the surface 30 turns easily upon the surface part IQ of the frame at the other end and a narrow strip of the surface between the surface parts 28 and 29 of the cover near the last mentioned end contacts with a narrow surface between the surfaces 8 and IQ of the side frame sections along which narrow strips, almost line contacts, the cover slides. surfaces l1 form almost vertical abutments for the cover whereby the possibility of a rectangular cover, opening on the longer way, that is to say across its shorter dimension, being carelessly handled and falling into the pit is definitely avoided. The surfaces I9 and 30 need only be radiused on two sides of the cover and frame but for convenience the radius is employed on all four sides.

Referring .to Figures 3 and 4, which show means for securing the cover positively in its frame when the cover is required to withstand gas or liquid pressure therebeneath in a manhole cover of lighter construction than that shown in Figures 1 and 2, the frame is cut away at each end usually on the centre line of the frame to receive and house a malleable casting 3|, vertical webs 32 of which project upwardly and fit Also the upper inside the channel of the frame between the main webs 22. The casting 3| is held in position by a soft iron rivet. 33 and a stainless steel or gunmetal screw 34 provided with a leather washer 35 passes through apertures in the cover casting into the casting 3| whereby the cover is positively secured thereto.

Figures 5 to 9 show three arrangements of corner jointfor'the frame. In Figures 5 and 8 each frame section is asshown in Figure 1, that is to say each section'consists of a straight side piece of the frame and a corner, all the seating surfaces and the top surface of the frame sections being radiused at the corners. In Figures 6 and -8 also each frame section consists of a the sections may be secured together in known .'manner bybolts passed through the bolt holes 36, hard white metal being run into the cham bers 3'! after the sections have been bolted together to key the. joint.

Figures 10 and 11 sh w part of a pipe line or ,cable trench cover in which the frame sections |5 are bolted and keyed together at 38 as described above. A series of covers l6 are provided andall the covers with the exception of the first of the series have a projecting part 89 at one end instead of the usual recessed part 30 whereby adjacent covers seat upon one another as shown. Except in very wide span trench covers long spans of clear opening, that is to say without cross members, may be covered satisfactorily in this manner. With wider span trench covers removable bars may be provided between the side frames on to which the covers seat, any

desired span of clear opening being obtainable in this manner by removal of the bars. Such an arrangement is shownin Figures 12 to -14 where the meeting ends of adjacent frame sections are cut away to receive the V-shaped end of the bar 40. openat the bottom and formed on both sides with seating surfaces ll, l8, IQ of the same form as those on the frame sections. A plurality of reinforcing rods 4| pass from end to end' of. the bar and are provided with eyebolts 42 which hold a stainless steel plate 43 to close the open bottom of the channel. The upper part of the bar is formed with apertures 44 through which concrete may be filled into the hollow cavity around the reinforcing rods 4|. The removable bar is supported by a rolled steel joist 45 and each end of the removable bar and steel joist is carried, in a cast iron housing 46 in which they are carried upon a second stainless steel plate 53 with a whitemetal backing 54. The removable I bar 40 is provided with a stainless steel screw 48 which on being screwed down against the cast iron housing causes the removable bar to lift to facilitate its removal. The cast iron housing is secured to the adjacent frame sections by bolts passing through the bolt holes 41 the joint being keyed by running white metal into the cavities 31. Grease grooves 49 are provided to render the joint between the bar 40 and'the frame sections |5 gasand water-tight. The cast iron housing 46- is rigidly held by a Lewis bolt 50 embedded in the concrete surround and passing through the eye 5|. In cases wheres The latter is of channel section construction of such strength is unnecessary the steel joist may be dispensed with.

What I claim and desire tosecure by Letters Patent is:-

1. A cast metal cover and frame construction for manholes, comprising a frame of inverted substantially U-shaped channel section adapted to be filled with concrete or the like, said section being also provided with openings at the top whereby the section may be filled either from the bottom or the top, the inner side wall of the channel being formed with a cover-seating surface extending continuously around the frame and from the top to the bottom, said surface being inclined over at least a part of its depth, and a cover having a seat conforming for close face toface contact from top to bottom with said cover-seating surface.

2. A cast metal cover and frame construction for manholes, comprising a frame of inverted substantially U-shaped channel section and having its inner side wall formed with a compositely curved cover-seating surface, and a cover having a seat conforming for close face to face contact with said compositely curved cover-seating surface, the latter operating substantially over its Whole area to support said cover and having a part capable of producing reaction to a force having a large vertical component exerted on the cover.

3. .A cast metal cover and frame construction for manholes according to claim 2, wherein said compositely curved cover-seating surface comprises an inclined part and a substantially horizontal part.

4. A cast metal cover and frame construction for manholes according to claim 2, wherein said compositely curved cover-seating surface consists of two upper and lower inclined parts separated by a substantially horizontal part.

5. A cast metal cover and frame construction for manholes, comprising a frame of channel section open at the bottom and adapted to be filled with concrete or the like, said section being provided with openings at the top whereby the section may be filled either from the bottom or the top, the inner side wall of the channel being 6. A cast metal cover and frame construction for manholes according to claim 2, wherein cross Webs are provided between the collateral parts of said inverted substantially U-shaped channel section which impart a more or less box or open grid formation to the frame.

'7. A cast metal cover and frame construction for manholes, comprising a frame composed of a plurality of channel sections open at the bottom and adapted to be filled with concrete or the like, said sections being provided with openings at the top whereby the sections may be filled either from the bottom or the top, the inner side walls of the sections being formed with cover-seating surfaces extending from the top to the bottom and inclined over at least a part of their depth, a cover having a seat conforming for close face to face contact from top to bottom with said cover-seating surfaces, and means for securing said plurality of frame sections together.

8. A cast metal cover and frame construction for manholes according to claim 7, wherein each frame section consists of a straight side piece and a corner piece.

9. A cast metal cover and frame construction for manholes, comprising a frame of inverted substantially U-shaped channel section having its inner side Wall formed with a cover-seating surface, cross bars removably located transversely of said frame between opposite sides thereof, said cross bars having side walls formed with similar cover-seating surfaces, 'and a plurality of covers having seats conforming for close face to face contact with said cover-seating surfaces, whereby large areas may be covered yet with the removal of said cross bars large spans of clear opening are obtainable.

VIVIAN ELKINGTON. 

